Responding to a Refresh Request in Android

This lesson shows you how to update your app when the user requests a manual refresh, whether the user triggers the refresh with a swipe gesture or by using the action bar refresh action.

Respond to the Refresh Gesture

When the user makes a swipe gesture, the system displays the progress indicator and calls your app’s callback method. Your callback method is responsible for actually updating the app’s data.

To respond to the refresh gesture in your app, implement the SwipeRefreshLayout.OnRefreshListenerinterface and its onRefresh() method. The onRefresh() method is invoked when the user performs a swipe gesture.

You should put the code for the actual update operation in a separate method, and call that update method from your onRefresh() implementation. That way, you can use the same update method to perform the update when the user triggers a refresh from the action bar.

Your update method calls setRefreshing(false) when it has finished updating the data. Calling this method instructs the SwipeRefreshLayout to remove the progress indicator and update the view contents.

For example, the following code implements onRefresh() and invokes the method myUpdateOperation() to update the data displayed by the ListView:

/*
* Sets up a SwipeRefreshLayout.OnRefreshListener that is invoked when the user
* performs a swipe-to-refresh gesture.
*/
mySwipeRefreshLayout.setOnRefreshListener(newSwipeRefreshLayout.OnRefreshListener(){@Overridepublicvoid onRefresh(){Log.i(LOG_TAG,"onRefresh called from SwipeRefreshLayout");// This method performs the actual data-refresh operation.// The method calls setRefreshing(false) when it's finished.
myUpdateOperation();}});

Respond to the Refresh Action

If the user requests a refresh by using the action bar, the system calls the onOptionsItemSelected() method. Your app should respond to this call by displaying the progress indicator and refreshing the app’s data.

To respond to the refresh action, override onOptionsItemSelected(). In your override method, trigger the SwipeRefreshLayout progress indicator by calling setRefreshing() with the value true, then perform the update operation. Once again, you should be doing the actual update in a separate method, so the same method can be called whether the user triggers the update with a swipe or by using the action bar. When the update has finished, call setRefreshing(false) to remove the refresh progress indicator.

Note: When the user triggers a refresh with a swipe action as described in Respond to the Refresh Gesture, you do not need to callsetRefreshing(). The SwipeRefreshLayout widget takes care of displaying the progress indicator and removing it when the update has finished. However, if the update is triggered by any means other than a swipe gesture, you need to explicitly turn the progress indicator on withsetRefreshing(). The method which actually refreshes the data calls setRefreshing(false) to signal that the update is finished.